Percutaneous surgery through a trocar inserted cannula and particularly with an opening through the external tissue of an animal or human, such as an abdominal wall has become an important means to minimize the extent of surgical invasion. The lessening of invasion improves the cosmetic result, shortens recovery and lowers the cost. Endoscopic or laparoscopic internal surgical procedures and equipment are available and in use for a variety of medical operations including gall bladder, bowel and gynecological surgery. A proper and simple instrument to safely open the pathway through the external tissue and provide a passage for surgical instruments such as laparoscopes, endoscopes and the like is needed.
U.S. Pat. No. 3,595,239 discloses a catheter tube having an obturator in the form of an electrode passing coaxially therethrough. The obturator electrode is connected to an electrosurgical generator in order to provide high frequency energy used to divide or cut tissue thereby forming a passage for the catheter coaxially about the obturator to pass therewith through the tissue. The tip of the obturator extends beyond the catheter tip and cuts the path for its passage. The catheter moves along with the obturator electrode by means of a ring disposed about the obturator proximal to the tip and inside the tip of the catheter. Disclosure of a safe approach and instrument for opening a pathway is missing.
A copending application incorporated by reference and made a part of this disclosure is U.S. Ser. No. 7-823093, assigned to a common owner. The disclosure in that application has a means for sensing the impedance or load associated with the energy required to do the cutting during insertion of an obturator tip so that the energy may be automatically ceased when the load has changed meaningfully. That approach, although useful with the trocar described therein, may for safe use be augmented by the combination of the circuitry described therein with the needle, stylet or trocar explained in this disclosure.
U.S. Pat. No. 4,232,676 has a knife blade which cuts and cauterizes the incision and in so doing self limits the current and blood flow at the knife. Specifically, the flat scalpel like blade carries electrodes therewith. A flat ceramic insulator supports the electrodes between which radio frequency current flows. Current flows when there is a conductive path between the electrodes. After cutting, the current cauterizes the incision sealing the wound and eliminating the current path. The cutting and coagulation are electrosurgical. The configuration and method for cutting and coagulation electrosurgically is bipolar so no teaching of monopolar cutting and coagulation appears. A monopolar tool and the dangers of changing loads realized upon reaching the inner cavity of the body remain unappreciated in the disclosure of U.S. Pat. No. 4,232,676.
The disclosures of U.S. Pat. Nos. 4,601,710 and 4,654,030, have background which is instructive of the procedures in common use and are therefore incorporated herein by reference and made a part hereof since they explain laparoscopic procedures with obturators in trocar tubes shielded by a sleeve. The obturators include sharpened tips that first pierce the external tissue and carry the trocar coaxially thereabout into the body. The shielding sleeve may project beyond the sharpened tip thereby covering and guarding it after entry into the body cavity. Various automatic mechanical mechanisms are disclosed that activate the shield after penetration. No electrosurgical cutting is taught to lower the effort required of the surgeon to penetrate the body wall. Considerable physical force and subsequent control are needed to effectively place the trocar through the abdominal wall without accidentally puncturing the bowels or other internal organs. The shielding is provided in recognition of the almost impossible dexterity required to make a proper penetration but the shielding has not eliminated the excessive force or the lighting quick reaction needed to drive the sharpened tip inward and stop before contact with an internal organ. Trocars are typically between 5 and 10 millimeters in diameter and the unit loading, (e.g. in units of kilograms per square millimeter) although reduced by the sharpened tip, is significant.
U.S. Pat. No. 4,535,773 discloses techniques for shielding the sharp tip of a trocar by either interposing an extensible shielding sleeve or retracting the trocar into its tube. With regard to the latter, a solenoid operated detent holds the trocar in an extended position relative its tube and electronic sensing in the tip of the trocar is used to activate the detent for release. Nothing in this reference has any disclosure of electrosurgical cutting with a tubular trocar with an impedance responsive circuit to regulate an electrosurgical generator, attached to an electrosurgical cutting tip. The sensors and switches are disclosed in conjunction with a probe which retracts during penetration. In particular, the probe extends beyond the cutting surface until the abdominal wall has been traversed. The sensors can be connected to an audible or visual signal to indicate completion of the puncture. The switches could be mechanical or magnetic, be tripped by a sleeve in the puncturing instrument, a probe or a spring wire protruding from the tip or blade of a sharp pointed cutter. Multiple sensors in the cutting probe and the cannula can be used to signal the penetration position.
U.S. Pat. No. 4,919,653 discloses a device for locating epidural space. The release of force on the tip of a needle triggers an alarm which activate a solenoid latch permitting the needle and its sleeve to move in a cannula in response to an activated electromagnet such that the distal end moves 2 mm into the epidural space. Pressure sensors detect when the depression or release of pressure occurs as the needle enters the epidural space. The pressure signal is converted to produce the voltage difference between the sensor and the potentiometer. This difference is shown on a meter. The pressure sensor can be a small membrane with electrical contacts which are closed in the unloaded position and open when the membrane moves when the epidural space is reached. The passage of current through the contacts keeps the circuit open by means of a relay.
U.S. Pat. No. 2,541,246 discloses a surgical instrument for sphincterotomy with a scissors handle to operate a distal shear. The cutting element is held retracted into the sheath by application of force to the scissors handle so the sheath may inserted through the common bile duct. The scissors handle is moved counterclockwise to open the cutting element and the sheath is withdrawn until the papilla is engaged. The cutting edge is toothed in the nature of a gripper to prevent the tissue from sliding from the grip of the cutting element during shearing. Reversing the movement of the scissors handle, i.e. clockwise, shears the sphincter of Oddi between the cutting element and the sheath. Thus cutting is effected by the scissors actuation of the cutting element not by axial movement of the sheath.
To safely place a cannula by a trocar technique requires knowledge of the position of the distal cutting tip thereof. The cutting edge, at the tip is used to open the passage for the cannula through the animal or human tissue of the abdominal wall. A device to eliminate the need to instantly indicate when the cutting tip has passed through the external tissue and reached the inside of the body is needed so that the internal organs are not injured. Because the organs fill the inside cavity and are close to the wall there is the possibility of injury before the surgeon can stop advancing the distal cutting tip. A lessening of the force required to penetrate will improve control and reduce the likelihood of accidental injury. This is particularly so wherein the control of the energy applied to the electrosurgery is regulated according to load.
It is known to place a Veress needle into the abdominal cavity to inflate the space therein so that the obturator/trocar combination can thereafter be forced through the abdominal wall. The Veress needle is relatively small, i.e. much smaller in diameter than a trocar which is about 10 mm. The distal tip of the Veress needle is typically not needle sharp but may be beveled or chamfered to ease manipulation into position through a scalpel cut through the tough external tissue of the abdominal wall. After placement in the cut and during penetration insufflation gas, typically carbon dioxide, is used to pressurize the abdominal cavity. If a sharp tipped needle is used without the scalpel cut the danger of piercing an internal organ exists so spring loaded shields are needed to protect the patient. With regard to use and design of Veress needles, "The Journal of Laparoendoscopic Surgery, Brief Technical Report", discloses laparoscopic needles and trocars and is referenced herein and incorporated as part of this disclosure.